Biomimicry of product properties for in vitro test development – wash resistance on sunscreen products

Case study and method development

The use of analysis on human volunteers for the evaluation of product properties, or to support commercial claims, entails implications. In vivo testing on human volunteers for product claims, such as sunscreen water resistance, raises ethical and cost concerns, limiting its use in R&D. To address this, predictive in vitro methods are needed to simulate in vivo results efficiently and affordably. These methods must use realistic substrates, replicate in vivo conditions accurately, and avoid false results. The case study describes the development of an in vitro test for sunscreen water resistance (2016–2017), designed to mirror in vivo SPF reduction after water exposure. This validated method supports R&D and extends testing to conditions like saltwater, chlorinated water, and sweat—scenarios unsuitable for human testing.